Agglomerate tabling of tungsten bearing ores



ug- 19, 1952 w. A. BATES AGGLOMERATE TABLING OF TUNGSTEN BEARING ORES 2:SHEETS-SHEET l Filed Feb. 4, 1948 /A/Vf/VTOR William A. Bates Aug. 19,1952 w. A. BATES n AGGLOMERATE TABLING OF TUNGSTEN BEARING ORES 2svHEETs-SHEET 2 Filed Feb. 4, 1948 FEED IN WATER IN 24 DRIVING RIFFLESSECr/o/'I/ A-A L A PLA/v v/EW PIG2A SHAKING TABLE F I G. 2

D. O E E E 1N F w I 4:5 f/w K E R/\` //D T/mw A b Na WILAW/ er ma? o0Hvmww/ s www vw E F. 52K MMM 7m D mm Cm M 4 /A .n R E m M m ,w T A A E WH H E S W. WA F FIG. B

WASH WATER FINE GANGUE STRATIFICATION BETWEEN RIFF'LES DISTRIBUTION OFSCHEELITE INAGGLOMERATE TABLING ON SHAKING TABLE F I G. 6

/NI/ENTOR William A, Baies FIG.

www

ITTOR/VE'I/s Patented Aug. 19, 1952 Umso STATES PATENT' omai-z;

G'GLMT TABLING' oF TNGSTN BEARING ORES William A. Bates,l Berkeley,Calif., assignonto California, Research Corporation, SanrFran'- cisco,Calif., a corporation of Delaware This invention pertains" to a' processfor beneciating tungsten-bearing minerals,v and more particularly to afroth `flotation process for beneciating scheelite. v

It is Well known that tungstenebearingniinerals, such as schee1ite, a recommonly found associated with otherminerals of metalliferousandnon-metalliferous nature. Thus; a typiealscheelite-bearing orer maycomprise' chalcopyrite and molybdenite, aswellas 'amiXedgangue ofcalcite, iluorite andthe like, 'and a considerableproportion ofsiliceous v co napolinds',A for example; quartz, garnet vand epidote. Nodiiiiculty is encountered inseparatingA simultaneously chalopyrite andmolybdenite by froth flotation' from` s'ucl1 an ore. TheCombined.ehalcbpifriimolybdnite consentrate is then readily retreatedfto yyield separate copper` and molybdenum concentrates by any methodsuitable for thei'lotatien ofw sulfiidev minerals. Then tailingsW'hchjar'e vObtained .from `the notationy of combined;chalcopyrite-molybdenite concentrate contain scheelite;calcite,4 uoriteand siliceous materials,

However, the recovery of s clfreelite fromthese tailings iS 110i Sesatisaciery, and. .straightforward the above lentiened Separation, ofcobperand I nolybde n1f.r'r1 l minerals from 'the[chaloopyritemolybdenite concentrate. As a: lmatter of' fact.,theapplication' of' conventional froth notation With"` anioni:collectors such as soaps 4of 'fatty acida; for4 example; of tallolacids, f or the Tc-@Very Uf scheen-te lCSJl- '.nj. ein', unduly 10Werad' f'V theftuilesteefbearilie"concentrate (only g/bbylwghlfofwoh The.@Satisfaetory grade of the concentrate is causedloy4 very similarfloatabilities of s clree11?3 1calcite andfluorite, all of whichhavea-eominon calcium ion and a similarchemicalconstitution; Calcite and3 Claims. (01.269449) nuorite tenero noatwithschente, as' de some ofthesiliceous constituents'jof the ore' pulp'g'and thus render-ftheproduotionjpf high grade Itungsten-bearing` concentrates difficultandjeostly.

1 lt Sthe primary Object of the'present invention t0 rrovdea'process forthe relcvry oftungstenbearing mineralsybylselective frotnotationnomconcomitantmetalliferous and nonemetalliferous contamin ntsin improvedAyield' and substantially high concentration.

' It is a further object of Vthis' invfention togp'rovide aprocess fortherecovery of tungstenbearing n iineralsA by selectiveifroth flotationthereofjfrom ore'svghich," in addition'td saltsof tungsten acids,comprise salts 0f other acids: with tion whichY enhances thevselectivity'of the ta'- tion process.

2 Y y An additional important object of the invention is rto provideavnevv process' for beneiicia'ting andv recovering tungsten-bearingminerals; which involves carrying out the flotation of said minerals-under controlledconditions of pl-lin order to insure selectiveflotation thereof from other components of theore pulp.

Still another particular object of the invention is4 to provide ajnevvand efficient process for the recoveryof high-grade tungsten-bearingminerals fro m metalliferous and nonmetalliferous contaminants thereofby selective froth notation and by lsubsequent tabling of thev floatedtungsten agglomerate. f

A more4 specie object "of the present invention i'siarwovdeapresfsffrthe rovery Qf. highlgrade scheelite from; an' ore pulpcontaining metalliferous and non-metalliferous contaminantsf'such ascalcite, luorite and silicates, byaselective froth ltatio'n'based en-the application of a particular eifeetive collector compositioncomprisinga naphthe'nic acid, or its soap; and a` neutral oil, 'WhileV`controlling the pli-fof the ore"pulp. v

Other objects of the invention will become obvious to those skilled inthe art'fromV the deto aloout-IQOL` However, thev optimum pH range forthe otation'of oalcite and iiuorite also lies in theneghberhooldjof thisfigure, and' as a result sleelit does' no t separate lfrorrr the otherconstituents' of the pulpf On the otherjhand, it is observed that inlthe pel-frange of about 117.5; and even at af pl-l of about ll,2,'allthree minerale:` selieelitqk ealoite and' uorite, rare simultaneouslydepressed inthe presence of a sapcolle'cto, and tatin ofneither can beihlvhed. Y :n Y 4 K It hasnovbeen diseovered that scheelite can beefffe'tively'f separated` from cale'ite, v fiuorite and most' ofthesileeouS' g2ie` in froth flotation by adjusting plofthe pulp toa valuehiglier than abuitA 10.5, andl preferably betweenv about 10.8 and about11.5'and even"higher, and apply ing a collector combination comprisinganaph-l therc acid; conveniently addedin'j the form of aS'fQ'B-illpl, aS'a S C 1 i 1 1i S 0D91lC, a neutral hydrocarbon oil to' effect' theselective flotatior')if of 'scheelite'.

Thisjregulation of priioupiee with the as dition of-Iieutral'hydrocarbon v oil to tliefnaplithenic acidcollector resultsY inconsiderable im- Weight of W03A as eompared With scheelite conncentrates heretofore obtained in the industry.

bearing minerals are not pure but contain from about 20% to about 50% byweight of unsaponiable hydrocarbons or neutral oil based on' thecombined Weight of oil-free acid and oil.

Neutral hydrocarbon oils may be added to these oil-containing naphthenicacids, as well as to pure acids, to secure the improved flotation electsof the present invention, provided the total content of neutralhydrocarbon oil in the collector combination does not exceed 50% byWeight of the combined weight of oil-free acid and oil. These oils arepreferably petroleum distillates, such as light fuel oils, boilingbetween about 350 P. and about '700 F. and having a flash point in therange from about 100 F. to about 250 F. and a viscosity less than about55 S. S. U. at 100 F.

In applying naphthenic acids or their soaps for preparing the collectorof the present invention to secure the best flotation results, effectiveproportions of neutral oil for enhancing the selective flotation of oremay be varied from about 20% to about 50%by Weight of the oil, based onthe total weight of the oil-free acid and oil in the combination. V

The true mechanism responsible for the depression o calcite, iluoriteand siliceous gangue and for the selective flotation of scheelite is notfully understood, but it is believed that in the presence of theeffective naphthenic acid soap collector, a mono-ionic coating ofcollector adheres to the surface of mineral particles, and, in

turn, adsorbs a second coating or layer of collector ions orientedreversely to the original layer, that is, with polar groups outwardly.This causes the mineral particles to become hydrophilic and unoatable.However, in the particular pH range of the present invention from 10.8to 11.5 and higher, the formation of this second layer of soap collectormolecules on the surface of scheelite particlesis less complete thanupon calcite and fluorite particles, and permits the replacement of thesecond layer of soap collector particles by a layer of the molecules ofneutral oil which are strongly adsorbed by the rst soap collector layerof particles and cause the selective flotation of scheelite.

It is noted that some siliceous material is oated along with thescheelite concentrate which floats in strongly agglomerated patches orclusters on the otherwise nearly clear froth. These clusters areair-bound and are held at the airwater interface. Since their apparentspecific gravity is lower than that of the floated siliceous gangue,this latter undesirable contamination Vmay be eliminated, andthe-scheelite concentrate upgraded by treating the froth carrying awaythe scheelite clusters by the method of agglomerate tabling.

In contradistinction to the conventional practice of tabling which isusually applied to recover materials too coarse to be levitated by frothflotation, the present invention resorts to tabling for the recovery ofline agglomerated scheelite which has been previously subjected to frothflotation, in a manner heretofore unknown in the art, as will bedescribed later on in this specification.

VWhen the selective froth flotation of the ore in accordance with theprocess of the present invention is followed by this tabling treatmentof thev agglomerated scheelite, the W03 content of the final concentrateis increased to a value as high as Ll0--50% by Weight of W03 as comparedwith the values of 10% to 12% of W03 obtained by comparable frothflotation methods, e. g., using tallol acids as collectors.

The operation of the process of this invention will be better understoodby reference to the drawing, wherein: Figure 1 represents a flowdiagraml of the step-by-step processing of a typical tungsten-bearingore in accordance with the invention; Figures 2 and 2A showdiagrammatically a, conventional shaking table; Figures 3 and 4represent the stratification of the constituents of the pulp betweentheriflles and the distribution of materials as they comejolf theshaking table respectively in a conventional. tabling treatment; Figures5 Yand 6 illustrate the stratification of the pulp between the riflesand the distribution of materials leaving the table as in the presentprocess. l j Y In the flow diagram'of lFigure 1 the tungstenbearing oreis fed to the process from mine l and undergoes a series of conventionalcrushing operations in a coarsecrusher 2 and fine crusher 3, beforebeing dumped into storage bin 4. The crushed ore is taken out from thestorage bin and subjected to grinding (milling) Ordinarily, such an oremay contain copper in the form of chalcopyrite, molybdenum in the formof molybdenite and tungsten in the form of scheelite. The otherconstitutents of the ore, theQgangue, may comprise calcite, fluoriteanda variety of siliceous minerals, chiey quartz, epidote and garnet.

Afterwet grinding. to a relatively coarse grind, for example, in aball-mill 5,fan aqueous pulp is formed which contains about 25% .byweight of solids in the form of ore particles-'not larger than 35 meshin size. This pulp proceedsto a conditioning tank 6 where it isconditioned with a mixture consisting of an appropriate conventionalcollecting reagent, suchas an alkyl thiophosphate, for example,di-isobutyl dithiophosphatafor potassium amyl xanthate, inan amount of,say, 0.01 pound per tone of ore to vfloat the chalcopyrite and,simultaneously, anadequate amount of pine oil or cresylic acid (e.f g.,0.1 poundper ton of ore), or other suitablefrothing agent for sulfideflotation, to act as a collector and frother for the molybdenite. In thediagram these conditioning agents are introduced into vconditioner 6from a mixingtank lUvialine Il.

Upon flotation in lsulfide flotation cells I2 theA combined sulfideconcentrate lor froth is sent through line I3 for additional processing,not shown inthe diagram, to'. obtain separate chalcopyrite vandmolybdenite' concentrates. 1 This processing of sulfide-bearing .frothlmayf consist,

for instance, in steamingto decompose the chalcopyritel collector andsubsequentlylfloating molybdenite away from chalc'opyritelwith the aidof additional frother, such as pin'e'loilor cresylic acid, supplemented,if desired, byanv addition of a small amount of neutral hydrocarbon oilof @the white-oil type.

In order to recover'scheelite by theprocess of selective froth flotationof. thepresent invention, the tailings from the V'flotation of combinedchalcopyrite-molybdenite concentrate are` sent to another conditioningtank I4 to be treated with chemical reagents prior to beginning theflotation step. The conditioning .treatment of the pulp formed by thesetailings maybe effected by forming a collector mixture in a mixing tankVl5 and introducing this mixture through line'l'into conditioning tankI4. The collector mixture in tank l5 comprises a naphthenic acid in theform of a soap^,'supplemented by a neutral hydrocarbon oil, the totalamount of the oil in the mixture varying from' about 20% to about 50% byWeight based on the combined Weight of the soap and oil. As mentionedhereinbefore, naphthenic acids effective as collectors in the flotationof scheelite have acid numbers ranging from about 160 to about 190maximum (on oil-free basis) andtheir unsapcniable hydrocarbon contentmay range from about to about 50% by Weight, provided the total contentof neutral oil in the collector combination is less than about 50% byweight basedon the combined weight ofthe oilfree acid and oil.Satisfactory selective flotation of scheelite is usually obtained byadjusting the pH of the pulp to al value of about 10.8 and upward priorto the vintroduction of naphthenic acid. Sodium carbonate and sodiumhydroxide are ordinarily added as pH regulators. In addition, thescheelite collector mixture may comprise a slime regulator anddepressant from siliceous materials, e. g., sodium silicate (specificgravity 40-41" Be), and a reagent, such asquebracho or a similartannin-bearing material, to promote the depression of calcite, fluoriteand siliceous sangue. fv In a typical case, the` fcallowing collectormixture may be used to condition the pulpprior to the flotation ofscheelite:

The conditioning treatment is effected by agitating the pulp with thereagents in tank I4 for at least 2 minutes in order to produce anintimate mixture, whereupon the pulp is fed into the rougher notationlcells Il. l I

The froth from these cells is directed into the cleaner flotation cells20, While the rougher tailings, upon introduction of additionalcollector and, if desiredgiof neutral oil from tank I8 are sent' to themiddling flotation cells 2l. Likewise, the tailings 'from the cleanercells maybe recycled vas shown by line 22,'if desired, to therougherflotation cells l1. From the' middling cells- 2| the froth isrecycled as shown by line 23 to be retreated in the rougher flotationcells l1, while the tailings are withdrawn to' the reject pond.

The froth produced in the cleaner cells and carrying agglomeratedclusters of vscheelite may be contaminated with some siliceous ganguewhich failed to become depressed, in spite of the critical adjustment ofpH- to between 10.8 and 11.15 and the' application of the novelcollector combination of the' present invention. In order to. free thescheelite-bearing froth from` thesev siliceous contaminants', it issubjected to agiglomerate tabling. Y Y y ,Y

' This latter operation is effected by utilizing any type ofconventional shakingl table, as shown diagrammatica-lly in Figures 2 and2A. A typical table 24 may be l5 feet'l'o'ng and 5 feet wide at thenarrow or concentrate end. Itsdeck is depth of Mi at the head and to afeather edge along the diagonal'line'of termination and spaced ll/apart. The table has a reciprocating motion parallel to itsv long axis,variablek from 230 to 280 strokes of about 3A" 'per minute. In theconventional tabling practi-ce`,f1the line heavy mineral 'particles aredeposited at the bottom between individualY riles', While coarse lightmineral is 'deposited at the top and is sheared off during the tablingoperation bythe downilow of water, partly because of the thickening ofthe underlying bed ofy heavy mineral values between the' riles andpartly because of the diminishing height `of the` riilies. Thestratification obtained Abetween the rilllesV and the" distribution ofthe various materials' as they leave the table in a conventional tablingoperation are shown in Figures Sand 4. A

In the tabling step of the present invention, as shown in the flowdiagram in Figure 1, the heavier tungsten' values in the cleanerconcentrate, agglon'ieratledl into airebound ocks which are coarser and`lighterthan the gangue, are'fed to shaking table 20;. These oc'ksstratify at the top between the riile's, are entrained by the flow oiWash water, and come oi the tailing side' of the table, as detailed inJFigures 5' and 6. The resulting scheelite concentrate is subjected todrying in drier 25'and iina'lly withdrawn to storage bin 2E?, v,whilethe' silic'e'os tailings, if desired, may be returned to the rougherflotation cells, as shown byline 27.

yThe novel application of agglomerate tabling to the recovery ofscheelite in accordance with the invention 'increases the W63 content ofthe cleaner flotation concentrate by as much as 10% by weight, while thetotal recovery of scheelite from the original ore-feedA by thepresentprocess is of the ordero'f' 90% byfwei'ght. Concentrates containing 40%to 50% and even more by Weight of WO2 are readily produced by resortingto the particular collector combinations of the invention,lmaintainingthe critical p-l range of the pulp and further concentratingand recovering tungsten values'b'y agglomeratie tabling` A number ofsnall scale' tests furnish the data which illustrate and emphasize theutility and advantagesr of the invention.

The ore'used in these 'tests' contained scheelite, calcite, nuorite,chalcopyrite and varioiis"v siliceous minerals. Ore samples werecrushedthrough No. 10 mesh in laboratory jaw Crushers and rolls, anulgrounds;A a 12" bau murat 5c R. P. M. Each' ball rnill cli'a'igeof4500"g".`of orer was ground for'ab'out 10 minuteswith 300Go'. of Water.

A typical screen analysisof'suchaV ground ore isgiven below in Table I:

TABLE I Direct Cumulative The mill `freed" analysis of this oreindicates the followingcontent mineral values:

Moszosy@ ,f cil-0.3 'No3-0.35

Flotation of chalcopyrite-molybdenite concentrate was Veffected in a'4600 g. Fagergren laboratory cell having a rotor speed of 1800 R. P. M.,

dilution of the pulp being about 25% solids for bothchalcopyrte-molybdenite and scheelite flotation. Chalcopyritemolybdenite concentrate was oated away with the aid of a collectorcombination comprising an alkyl thiophosphate co1- lector forchalco'pyrite, such as di-isobutyl dithiophosphate (0.01 to, 0.05 poundper ton), and pine 'oil acting asY a collector and frother Vformolybdenite (0.1 to 0.15 pound per ton).

In the subsequent tests of molybdenite otation,` the effects of additionf various hydrocarbon oils'on the grade of molybdenite concentrate werecompared. Two neutral hydrocarbon oils were used: A-a heavy aromatic oilhaving an A.,P. I. gravity of 13.9, and boiling between about 400 F. andabout 700 F.; and oil "--obtained by polymerization of butenes andhaving a viscosity of about 222 S. S. U. at 210 F. The maximum ofimprovement in collection eciency was noted in the case of a collectorcombination: di-isobutyl dithiophosphate (0.007 pound per ton) pine oil(0.12 pound per ton) and neutral oil B (1 pound per t0n).

The results of these tests of molybdenite recovery are tabulated inTable II. The analyses of the concentrates and middlings were made bymeans of a polarograph, while those of the tailings by means of aspectograph.

TABLE II Eect of oils upon flotation of molybdemte After the removal vofthe chalcopyrite-molybdenite concentrate the scheelite-bearing tailingswere reconditioned for about two minutes with a mixture of the followingreagents:

Y Lbs. per ton Sodium carbonate, a pH regulator 5.0 Sodium silicate (40B.) a slime regulator 5.0 Quebracho, a depressant for silicates andquartz 0.5

Thereupon .75 pound per t0n of oil-free naphthenic acid in the form 0fsodium soapv was added to a similar batch of scheelite-bearing tailings,and the sample subjected to flotation in the rougher flotation cells.

The acid used in these tests has been originally o of w03).

8 obtained by extraction of a lubricating oil fraction and"containedabout 43% by weight of Vunsaponiablematerial; it was dissolved in dilutesodium'hydroxide soluton and repeatedly ex.-

tracted with petroleum ether until substantially all Vsaponiable Yoilshave been removed from it, whereupon it -was acidied to yield anoil-free naphthenic acid'v having an acid number of approximately 177and a specific gravity of 0.97.

10 Upon withdrawing a rougher scheelite froth, an

additional 0.75 pound per ton of oil-free naphthenic .acid in the formof sodium soap was added to the rougher tailings and a middling frothremovedA from the corresponding flotation cells. The remaining materialVconstituted thev final rougher tailings. The rougher froth product wasrefloated in fresh water upon the addition of 0.25 poundper ton ofnaphthenic acid (as sodium naphthenate), and 1 pound per ton of sodium 0carbonateV toA yield a final cleaner concentrate In this first test thepI-Ivof the pulp was equal throughout to 10.0. Two other tests, Nos. 2and 3, were carried out at a higher pH of 11.2, which was achieved bythe introduction of about 4 pounds per ton of sodium hydroxide prior tothe recovery of rougher flotation froth and of additional 2 pounds perton of sodium hydroxide prior to the recovery of final cleaner froth. Inthe last test, No. -3, the oil-free naphthenic acid (as sodiumnaphthenate) was applied together with about 0.75 pound per ton ofneutral hydrocarbon oil, namely, a light petroleum fuel oil which boiledin the range from about 360 F. to about 684 F. and had a gravity valueof 31.9 A. P. I., a ash point 0f 174 F., and a viscosity of 37.1 S. S.U. at

100 F. The cleaner froth product from all three tests was subjected to aform of agglomerate separation (tabling) by using a vanning plaque forthe purpose, except in test No. 1 where the amount o of cleaner frothwas too small to permit separa- .tion.

The'results of flotation tests Nos. 1, 2 and 3 are ypresented in TableIII and indicate that a pH equal to 10.0, the application of oil-freenaphthenic acid as a notation agent results in a low recovery of W03equal to 50.8% by weight of the totalxWOs in the ore, even though thecleaner concentrate grade is rather high (58.7% by weight Increasing thepH to 11.2 depresses the scheelite and reduces both the concentrategrade and the total recovery, notwithstanding the application ofagglomerate tabling. However, upon addition of neutral hydrocarbon oilin test No. 3, the concentrate grade was markedly improved and a verysatisfactory recovery value of 61.9% was attained.

. TABLE III Test No. 1, i Test No. 2, Test No: 3' pH=10.0 Qil-freepH=ll.2 Oil-free llerHllz Ou'fre Naphthemc Amd Naphthenic Acid aggIfellfafl Percent Percent Percent Percent Percent Percent P r t PPercent Total Total e .Cen ement Weight W0; WOa Welght W03 Wol WeightWO; 'Jazl Agglfomerate Concenm n 0. e1 21. 5 32. 2 0.53 47 0 61 9Aggmmerate railing 0.51 18. 2 22. s geaner gonhclentrate g. 52.1 Y5(8).225 0 20 37'4 18' 4 eanr a1' g 1 2.12 1.4 1.4 5.78 Midd1mg 5.8 .5814.1 11.2 0. 35 9.6 11.4 339 l2 Rougher Ta11ing. 82. 9 05 16. 9 81. 40.14 28.0 79. 0 0. 03 5 9 Sulde Concentrate l0. 3 4. 2 3, 1

Heads-- 0.24 41 41 anotner group of." tests 4J .5. and 6, were enactedbyI following the ame procedure as de- 10 With the nanlithenicacidrneiitral hydrocarbon oil collective combinations. in whichtheproporseriedfor tests 1; :2 and 3. However. in tion of neutralhydrocarbon oil. Whether Oriel-- these. tests the nanhtnenic acid wasaconnneroial nallv in the. acid or Subsequently added thereto, gradenaphthenic acid added in the form of so- 5 does not exceed 50% byWeishtbased on the comdiiirnsoap, having an acid number on oil-freebined Weight of the oil and acid, compared with basis canal to, ll'andcontaining 30% by weight the results obtainedwi-th naphthenic acidwith-V ofunsapcninable matter. The other reagents and Ollt neutral Oil,0I' With a naphthenc acid-.neutral test conditions were identical withthose applied Oil COmbnatQn containing neutral oil in excess in tests.1, z and 3 except forth@ fact that 1.0V 10 of 50% by Weight, or with acombination of a pound per ton of naphthenic acid was used to fatty aCd01 its S0510 With neutral Oilloat the rougher and middling concentrates,in- The antlySiS O f tungsten fnntent as represtead of 0.75 pound perton. The results presented in tile ttbuifted dat@ Was effected as foi'sen-ted in Tapie 1v show that with the higher pH IOWS: Ore. Salnlelnswere treated with an acid, equal to 11.2, the application of commercialgrade l5 Dlefefibly hydrochloric, in Order to decomposel naphthenic acidcontainingabout 30% by weight seheellte and to precipitate most tungstenas of unsaponiable material as a flotation agent tungstlc acid Theremainder WaS lteled and improves the recovery o'fscheelite as shown bywattted and finality eXtraCted With DOtaSSium 115- the values determinedfor agglomerate conceniK-Xldef the iCSllltng Potassium tungstate S0111-trate. However, the addition' of neutral oil to 20 non bemg thereafter@Cidied and treated With this acid in the amountof .'15 pound per? tonin a emes-S of alpi-1a benzonoxime' The* greci-mi' test NQ 6 showed verydefinitely that such an gtdsungsten complex was ltered and ignitedlflidllile,csglnbgtlettaopomon egg-nin It hasbeen observed that incertain instances, f l am gv e e l f-g 25 the eiiiciencyof selectivenotation according to 59% by Weight Qf. they total Weight 0f acid andthe process of this invention may be adversely af- 011, an adverseeecton the IeCOVelY Of fected by the hardness of water used. Coarse andsoheelite. heavy flocks or tungsten minerai wiii then be TABLE IV Y eTest No.6,

,- pantitiftntnag pealtesdiitaim pngai-gjelgggalag Naphthenic AcidNaphthemo Acid Neutl Oi? Percent Percen eliel'-lercent ,lva PceitTotali; Pant PIiiit Agglomerate Concentrate. Agglomerate Telling CleanerConcentrate.

Sultlde Concentrate Heads In addition, tests were carried out with oleicacid (test, No. 7) and semi-.refined tallol acid (test N028), applied inthe form of their sodium soaps, at a pH' of 11.2 and'vvith the additionof the same amount of the neutral hydrocarbon oil as u secl in precedingtests Nos. 4, 5 and 6. 'The test data presented in Table V showvunambiguously that the improvement in the selectivity of sclieelitenotation in the pHrange from 10.8 t0

,present invention will require softening whenever its hardnessapproaches about 88 p. n. mof calcium ion.

11.5 are peculiar of the naplithenic acidfneutral 55 The new process isnot limited by the exampes hydrocarbon oil collector combination of thenor by the QW diagram dSfSQlibed herenabve, presentv invention and thatfatty acids are unand includes Within its scope all the modicatonsSuitable for the use in combination with such and variations.. thereof,except as limited by the neutral oils. appended claims. Thus, forexalgrple2 the quanti- TABLE V Test No. 7 Test No. 8 PH.=11.2 oleic Acidpnaiiz Tauoioii Neutral Oil Neutral O11 Percent Percent Percent PercentPercent Percent 1 weight Wo '$521. Weight wo wg?.

Agglomerate Concentrate.-- 0.05 16.6 1.4

Agglomerate Taling 0.05 28.4 2.5

Cleaner Concentrate.. 0. 05 35. 4 3. 1

Cleaner Tailng. 0. 3 16. 6 9.0 0. 92 34. 3 53. 5

Middling e. 1 c. 3 69. i o. to 1o. 6 1o. s

Rougher railing... eo. 9 0.11 18.0 9o. 1 o. 2o 32. e

Sulde Concentrate.. 2.6 2. 3

Heads 0 56 0.59

The data from the above tests clearly point out the superiority of thenotation results Obtained ties of the various reagents may be varied tosuit the requirements of each particular case;

1l likewise, the rougher concentrate may be cleaned and recleaned asmany times as desired. Furthermore, other eflicient collectors andfrothers than pine oil and alkyl thiophosphates may be used for therecovery of copper and molybdenum values described hereinbefore.

In 'summarizing the various significant improvements over the prior artsecured by this invention, the following important features thereof areemphasized:

(l) Production of high grade tungsten concentrates largely superior tothose previously obtained in the art is'now made possible;

(2) The grade of tungsten concentrate may be further improved by theapplication of agglomerate tabling to remove persisting siliceouscontamina'nts';

^ (3) High amounts o f tungsten minerals vmay be recovered fromtungsten-bearing ores by selective flotation in the alkaline pI-I rangeof 10.8 to 11.5 with'the'aid of heavy naphthenic acids as flotationcollectors improved by the addition fof neutral hydrocarbon oil.

It is finally stressed that this invention is not limited to theflotation of scheelite away from calcite and iuorite;v but that thisprocess may also be successfully used to recover tungsten minerals fromany type of tungsten-bearing ore, wherein other constituents have thesame or an equivalent cation, such as calcium or magnesium and,therefore, cannot be floated away from each other by conventionalflotation procedures. For "instance, it is possible to separatescheelite from ores containing, e. g.,pscheelite and magnesite, or

from ores containing scheelite, apatite and anhydrite.

As mentioned above, many modifications may be made in the process of theinvention without departing from the spirit thereof, its scope beinglimited solely by the definitions in the appended claims.

I claim:

1. In a process of recovering scheelite from an ore pulpcontainingscheelite, calcite, fluorite and siliceous gangue and having a pH ofbetween about '10.8 and'about. 11.5, the combination of steps ofconditioning said pulp with sodium silicate as a slime regulator and atannin-containing depressant for said calcite, uorite, and siliceousgangue; effecting selective flotation of scheelite away :fromh saidcalcite, iluorite, and siliceous gangue contained in said pulp in thepresence of a collector combination comprising a soap of a naphthenicacid having an acid number on oilfree basisbetween about 160 and about190 maximum, and, further comprising from about 20% toless than about50% by weight of afneutral petroleum hydrocarbon oil boiling betweenabout 350 F. and about 700 F. and having a viscosity of less than about55 S. S. U. at 100 F., based on the total weight of oil-free acid andoil.

2. In a process of recovering scheelite from an ore pulp containingscheelite, calcite, uorite and siliceous gangue and having a pH ofbetween about 10.8 and about 11.5, the combination of steps ofconditioning said pulp with sodium silicate as a slime regulator andquebracho as a degangue; effecting selective vnotation of scheelite awayfrom said calcite, iluorte, and siliceous gangue contained in said pulpin the presence of a collector combination comprising a soap of anaphthenic acid having an acid number on oilfree basis between about 160and about 190 maX- imum, and further comprising from about 20% to lessthan about 50% by weight of a neutral petroleum hydrocarbon oil boilingbetween about 350 F. and about 700 F. and having a viscosity of lessthan 55 S. S. U. at 100 F., based on the total weight of oil-free acidand oil.

3. In a process of recovering scheelite from an ore pulp containingscheelite, calcite, fluorite and siliceous gangue and having a pI-I ofbetween about 10.8 and about 11.5, the combination of steps ofconditioning said pulp with sodium silicate as a slime regulator andquebracho as a depressant for said calcite, uorite and siliceous gangue;effecting said selective flotation of scheelite away from said calcite,fluorite and siliceous gangue contained in said pulp in the presence ofa collector combination comprising a soap of a naphthenic acid having anacid number between about 160 and about'190 maximum on oil-free basis,and further comprising from about 20% to less than about 50% by weightof a neutral petroleum hydrocarbon oil boiling between about .350 F. andabout 700 F. and having a viscosity of less than 55 S. S. U. at 100 F.,based on the total weight of oil-free acid and oil; recovering theresultant supernatant oat of light air-bound clusters of scheeliteparticles; and floating away said supernatant clusters of scheeliteparticles from the underlying heavier siliceous gangue of said iloat byagglomerate tabling.

WILLIAM A. BATES.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,319,129 Wells Oct. 2l, 19191,953,431 Patek Apr. 3, 1934 2,069,365 Handy Feb. 2, 1937 2,094,646Frantz Oct. 5, 1937 2,105,827 Tartaron Jan. 18, 1938 2,120,485 Clemmeret al. June 14, 1938 2,216,992 Vogel-Jargensen Oct, 8, 1940 2,303,962Tartaron et al Dec. 1, 1942 2,373,305` Gieseke Apr. 10, 1945 2,395,639Monson Feb. 26, 1946 2,442,455 Booth June 1, 1948 2,464,313 Weinig Mar.15, 1949 OTHER REFERENCES Gaudin, Principles of Mineral Dressing (c),1939, by McGraw-Hill Book Company, pages 387-388.

The Mineral-Industry during 1939, vol. 48 (c),

` 1940, page 673.

pressant for said calcite, uorite, and siliceous Y Engineering andMining Journal, April 1943, p. 66.

Taggart, Handbook of Mineral Dressing (c),

1945, section 12, page 13.

1. IN A PROCESS OF RECOVERING SCHEELITE FROM AN ORE PULP CONTAININGSCHEELITE, CALCITE, FLUORITE AND SILICEOUS GANGUE AND HAVING A PH OFBETWEEN ABOUT 10.8 AND ABOUT 11.5, THE COMBINATION OF STEPS OFCONDITIONING SAID PULP WITH SODIUM SILICATE AS A SLIME REGULATOR AND ATANNIN-CONTAINING DEPRESSANT FOR SAID CALCITE, FLUORITE, AND SILICEOUSGANGUE; EFFECTING SELECTIVE FLOTATION OF SCHEELITE AWAY FROM SAIDCALCITE, FLUORITE, AND SILICEOUS GANGUE CONTAINED IN SAID PULP IN THEPRESENCE OF A COLLECTOR COMBINATION COMPRISING A SOAP OF A NAPHTHENICACID HAVING AN ACID NUMBER ON OILFREE BASIS BETWEEN ABOUT 160 AND ABOUT190 MAXIMUM, AND FURTHER COMPRISING FROM ABOUT 20% TO LESS THAN ABOUT50% BY WEIGHT OF A NEUTRAL PETROLEUM HYDROCARBON OIL BOILING BETWEENABOUT 350* F. AND ABOUT 700* F. AND HAVING A VISCOSITY OF LESS THANABOUT 55 S.S.U. AT 100* F., BASED ON THE TOTAL WEIGHT OF OIL-FREE ACIDAND OIL.